[x264-devel] Vertical 'flickering' problem/bias in x264?

[Derek Buitenhuis]

I've noticed on several 4:2:0 input files of screecasts (lots static images and text), that
x264 seems to exhibit a vertical (as in it does not happen when one uses 4:2:2 or 4:4:4
output) 'flickering' problem on some static antialiased text -- specifically, ClearType.

I can consistently reproduce it with a few source files, which I can share privately with
the x264 developers if need be, using something akin to:

    x264 --crf 20 --preset medium -o output.h264 input.ext

A small encoded sample of the problem is available here:

    http://chromashift.org/flicker.mp4

Look at 0:40-0:50 at the word 'vragen'.

Any thoughts on this? Perhaps it's expected behavior?

- Derek